Transforaminal versus posterior lumbar interbody fusion for symptomatic single-level spondylolisthesis (LIFT): a multicentre controlled, patient blinded, randomised non-inferiority trial.

Background: The effectiveness of transforaminal lumbar interbody fusion (TLIF) compared to posterior lumbar interbody fusion (PLIF) in patients with single-level spondylolisthesis has not been substantiated. To address the evidence gap, a well-powered randomized controlled non-inferiority trial comparing the effectiveness of TLIF with PLIF, entitled the Lumbar Interbody Fusion Trial (LIFT), was conducted. Methods: In a multicenter randomized controlled non-inferiority trial among five Dutch hospitals, 161 patients were randomly allocated to either TLIF or PLIF (1:1), stratified according to study site. Patients and statisticians were blinded for group assignment. All patients were over 18 years old with symptomatic single-level degenerative, isthmic or iatrogenic lumbar spondylolisthesis, and eligible for lumbar interbody fusion surgery through a posterior approach. The primary outcome was change in disability measured with the Oswestry Disability Index (ODI) from preoperative to one year postoperative. The non-inferiority limit was set to 7.0 points based on the MCID of ODI. Secondary outcomes were change in quality-adjusted life years (QALY) assessed with EuroQol 5 Dimensions, 5 Levels (EQ-5D-5L) and Short Form Health Survey (SF-36), as well as back and leg pain (Numerical rating scale, NRS), anxiety and depression (Hospital Anxiety Depression Scale; HADS), perioperative blood loss, duration of surgery, duration of hospitalization, and complications. Trial registration: Netherlands Trial Registry, number 5722 (registration date March 30, 2016), Lumbar Interbody Fusion Trial (LIFT): A randomized controlled multicenter trial for surgical treatment of lumbar spondylolisthesis. Findings: Patients were included between August 2017 and November 2020. The total study population was 161 patients. Total loss-to-follow-up after one year was 16 patients. Per-protocol analysis included 66 patients in each group. In the TLIF group (mean age 61.6, 36 females), ODI improved from 46.7 to 20.7, whereas in the PLIF group (mean age 61.9, 41 females), it improved from 46.0 to 24.9. This difference (-4.9, 90% CI -12.2 to +2.4) did not reach the non-inferiority limit of 7.0 points in ODI. A significant difference in the secondary outcome measurement, QALY (SF-36), was observed in favor of TLIF (P < 0.05). However, this was not clinically relevant. No difference was found for all other secondary outcome measurements; PROMs (EQ-5D, NRS leg/back, HADS), perioperative blood loss, duration of surgery, duration of hospitalization, and perioperative and postoperative complications. Interpretation: For patients with single-level spondylolisthesis, TLIF is non-inferior to PLIF in terms of clinical effectiveness. Disability (measured with ODI) did not differ over time between groups. Funding: No funding was received for this trial.

Advocating uniformity in spine surgery: a practical disease-specific guideline for trial-based economic evaluations.

OBJECTIVES: Despite the availability of general and national guidelines for the conduct and reporting of economic evaluations, there is heterogeneity in economic evolutions concerning spine surgery. This is partly the result of differing levels of adherence to the existing guidelines and the lack of disease-specific recommendations for economic evaluations. The extensive heterogeneity in study design, follow-up duration and outcome measurements limit the comparability of economic evaluations in spine surgery. This study has three objectives: (1) to create disease-specific recommendations for the design and conduct of trial-based economic evaluations in spine surgery, (2) to define recommendations for reporting economic evaluations in spine surgery as a complement to the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) 2022 checklist and (3) to discuss methodological challenges and defining the need for future research. DESIGN: A modified Delphi method according to the RAND/UCLA Appropriateness Method. SETTING: A four-step process was followed to create and validate disease-specific statements and recommendations for the conduct and reporting of trial-based economic evaluations in spine surgery. Consensus was defined as >75% agreement. PARTICIPANTS: A total of 20 experts were included in the expert group. Validation of the final recommendations was obtained in a Delphi panel, which consisted of 40 researchers in the field who were not included in the expert group. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome measure is a set of recommendations for the conduct and reporting, as a complement to the CHEERS 2022 checklist, of economic evaluations in spine surgery. RESULTS: A total of 31 recommendations are made. The Delphi panel confirmed consensus on all of the recommendations in the proposed guideline. CONCLUSION: This study provides an accessible and practical guideline for the conduct of trial-based economic evaluations in spine surgery. This disease-specific guideline is a complement to existing guidelines, and should aid in reaching uniformity and comparability.

Methodology of economic evaluations in spine surgery: a systematic review and qualitative assessment.

OBJECTIVES: The present study is a systematic review conducted as part of a methodological approach to develop evidence-based recommendations for economic evaluations in spine surgery. The aim of this systematic review is to evaluate the methodology and quality of currently available clinical cost-effectiveness studies in spine surgery. STUDY DESIGN: Systematic literature review. DATA SOURCES: PubMed, Web of Science, Embase, Cochrane, Cumulative Index to Nursing and Allied Health Literature, EconLit and The National Institute for Health Research Economic Evaluation Database were searched through 8 December 2022. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies were included if they met all of the following eligibility criteria: (1) spine surgery, (2) the study cost-effectiveness and (3) clinical study. Model-based studies were excluded. DATA EXTRACTION AND SYNTHESIS: The following data items were extracted and evaluated: pathology, number of participants, intervention(s), year, country, study design, time horizon, comparator(s), utility measurement, effectivity measurement, costs measured, perspective, main result and study quality. RESULTS: 130 economic evaluations were included. Seventy-four of these studies were retrospective studies. The majority of the studies had a time horizon shorter than 2 years. Utility measures varied between the EuroQol 5 dimensions and variations of the Short-Form Health Survey. Effect measures varied widely between Visual Analogue Scale for pain, Neck Disability Index, Oswestry Disability Index, reoperation rates and adverse events. All studies included direct costs from a healthcare perspective. Indirect costs were included in 47 studies. Total Consensus Health Economic Criteria scores ranged from 2 to 18, with a mean score of 12.0 over all 130 studies. CONCLUSIONS: The comparability of economic evaluations in spine surgery is extremely low due to different study designs, follow-up duration and outcome measurements such as utility, effectiveness and costs. This illustrates the need for uniformity in conducting and reporting economic evaluations in spine surgery.

Factors associated with an increased risk of developing postoperative symptomatic lumbar spondylolisthesis after decompression surgery: an explorative two-centre international cohort study.

PURPOSE: Symptomatic lumbar spinal stenosis can be treated with decompression surgery. A recent review reported that, after decompression surgery, 1.6-32.0% of patients develop postoperative symptomatic spondylolisthesis and may therefore be indicated for lumbar fusion surgery. The latter can be more challenging due to the altered anatomy and scar tissue. It remains unclear why some patients get recurrent neurological complaints due to postoperative symptomatic spondylolisthesis, though some associations have been suggested. This study explores the association between key demographic, biological and radiological factors and postoperative symptomatic spondylolisthesis after lumbar decompression. METHODS: This retrospective cohort study included patients who had undergone lumbar spinal decompression surgery between January 2014 and December 2016 at one of two Spine Centres in the Netherlands or Switzerland and had a follow-up of two years. Patient characteristics, details of the surgical procedure and recurrent neurological complaints were retrieved from patient files. Preoperative MRI scans and conventional radiograms (CRs) of the lumbar spine were evaluated for multiple morphological characteristics. Postoperative spondylolisthesis was evaluated on postoperative MRI scans. For variables assessed on a whole patient basis, patients with and without postoperative symptomatic spondylolisthesis were compared. For variables assessed on the basis of the operated segment(s), surgical levels that did or did not develop postoperative spondylolisthesis were compared. Univariable and multivariable logistic regression analyses were used to identify associations with postoperative symptomatic spondylolisthesis. RESULTS: Seven hundred and sixteen patients with 1094 surgical levels were included in the analyses. (In total, 300 patients had undergone multilevel surgery.) ICCs for intraobserver and interobserver reliability of CR and MRI variables ranged between 0.81 and 0.99 and 0.67 and 0.97, respectively. In total, 66 of 716 included patients suffered from postoperative symptomatic spondylolisthesis (9.2%). Multivariable regression analyses of patient-basis variables showed that being female [odds ratio (OR) 1.2, 95%CI 1.07-3.09] was associated with postoperative symptomatic spondylolisthesis. Higher BMI (OR 0.93, 95%CI 0.88-0.99) was associated with a lower probability of having postoperative symptomatic spondylolisthesis. Multivariable regression analyses of surgical level-basis variables showed that levels with preoperative spondylolisthesis (OR 17.30, 95%CI 10.27-29.07) and the level of surgery, most importantly level L4L5 compared with levels L1L3 (OR 2.80, 95%CI 0.78-10.08), were associated with postoperative symptomatic spondylolisthesis; greater facet joint angles (i.e. less sagittal-oriented facets) were associated with a lower probability of postoperative symptomatic spondylolisthesis (OR 0.97, 95%CI 0.95-0.99). CONCLUSION: Being female was associated with a higher probability of having postoperative symptomatic spondylolisthesis, while having a higher BMI was associated with a lower probability. When looking at factors related to postoperative symptomatic spondylolisthesis at the surgical level, preoperative spondylolisthesis, more sagittal orientated facet angles and surgical level (most significantly level L4L5 compared to levels L1L3) showed significant associations. These associations could be used as a basis for devising patient selection criteria, stratifying patients or performing subgroup analyses in future studies regarding decompression surgery with or without fusion.

Process Evaluation of Lumbar Interbody Fusion Surgeries in Five Dutch Hospitals: A Qualitative Analysis.

Background and Objectives: Only limited qualitative research concerning instrumented spine surgeries has been published, despite the increasing number of these surgeries and the evident importance of qualitative analysis of the processes surrounding these complex interventions. Current qualitative research is mainly limited to the experiences, emotions and expectations of patients. Insight into the full process, including experiences from the perspective of informal caregivers and healthcare professionals, remains scarce. Materials and Methods: Data were gathered by means of semi-structured face-to-face interviews. In total, there were 27 participants, including 11 patients, 7 informal caregivers and 9 healthcare professionals. The interview process was audiotaped, and each interview was transcribed verbatim. To systematically analyse the gathered data, software for qualitative analysis (NVivo) was used. After immersion in the raw data of transcripts and field notes, a list of broad categories for organising the data into meaningful clusters for analysis was developed. All interviews were coded by the first author, and 25% was independently assessed by the second author. Results: The results of our study describe several promoting and limiting factors concerning the process of lumbar fusion surgery from the perspective of patients, informal caregivers and healthcare providers. The most frequently mentioned promoting factors were: information and opportunities to ask questions during consultations; multidisciplinary consultations; good communication and guidance during hospitalization; and follow-up appointments. The most frequently mentioned limiting factors were: lack of educational material; lack of guidance and communication prior to, during and after hospitalisation. Conclusion: Overall, participants were satisfied with the current healthcare-process in lumbar fusion surgery. However, we found that lack of educational material and guidance during the process led to insecurity about complaints, surgery and recovery. To improve the process of lumbar interbody fusion and to increase patient satisfaction, healthcare providers should focus on guiding and educating patients and informal caregivers about the pre-operative trajectory, the surgery and the recovery. From the healthcare providers' perspective, the process could be improved by multidisciplinary consultations and a dedicated spine team in the operation room. Although this study focusses on lumbar fusion surgery, results could be translated to other fields of spine surgery and surgery in general.

Evidence-based recommendations for economic evaluations in spine surgery: study protocol for a Delphi consensus.

INTRODUCTION: Considering the rising global healthcare expenses, economic evaluations are more important than ever. Even though the number of studies regarding costs and cost-effectiveness is increasing, the quality of these studies remains relatively low. This is mainly caused by abundant heterogeneity in methods used for determining, calculating and reporting cost data, despite current general guidelines for the conduct of economic evaluations. Disease-specific recommendations for the conduct of economic evaluations in the field of spine surgery, as complement to existing general guidelines, will ameliorate overall research quality, comparability and interpretability and thus, the overall quality. We aim to provide expert-based recommendations for the design, conduct, and reporting of economic evaluations in spine surgery. METHODS AND ANALYSIS: A modified Delphi study will be conducted to formulate expert-based recommendations. The following steps will be taken:(1) The conduct of a systematic review to identify relevant publications and identify relevant authors. Formation of an expert group and a Delphi-panel. (2) Drafting of statements based on articles included in the systematic literature review. Validation of drafted statements by the expert group. Step 2 can be repeated up to three times, statements can be discarded and adjusted in these rounds. Statements with more than 75% agreement will be accepted as consensus statements. (3) Validation of statements by the Delphi-panel. (4) Final recommendations. ETHICS AND DISSEMINATION: The underlying work is based on existing literature and published data and does not include participation of patients, and thus does not require ethical review approval. The final recommendations are intended for (clinical) researchers in the field of cost-effectiveness in spine surgery. The Delphi method ensures that the final output reflects the opinions of international participants and gives insight in the adherence level to the recommendations. The aim is to reach uniformity in design, conduct and reporting of these studies, as is currently lacking. This will provide a solid basis to determine cost-effectiveness of spine surgeries and consequently aid to limit the rising healthcare costs. The findings of this study and the final recommendations will be disseminated in conferences and seminars and will be published in an international peer-reviewed journal.

Comparison of (Partial) economic evaluations of transforaminal lumbar interbody fusion (TLIF) versus Posterior lumbar interbody fusion (PLIF) in adults with lumbar spondylolisthesis: A systematic review.

INTRODUCTION: The demand for spinal fusion surgery has increased over the last decades. Health care providers should take costs and cost-effectiveness of these surgeries into account. Open transforaminal lumbar interbody fusion (TLIF) and posterior lumbar interbody fusion (PLIF) are two widely used techniques for spinal fusion. Earlier research revealed that TLIF is associated with less blood loss, shorter surgical time and sometimes shorter length of hospital stay, while effectiveness of both techniques on back and/or leg pain are equal. Therefore, TLIF could result in lower costs and be more cost-effective than PLIF. This is the first systematic review comparing direct and indirect (partial) economic evaluations of TLIF with PLIF in adults with lumbar spondylolisthesis. Furthermore, methodological quality of included studies was assessed. METHODS: Searches were conducted in eight databases for reporting on eligibility criteria; TLIF or PLIF, lumbar spondylolisthesis or lumbar instability, and cost. Costs were converted to United States Dollars with reference year 2020. Study quality was assessed using the bias assessment tool of the Cochrane Handbook for Systematic Reviews of Interventions, the Level of Evidence guidelines of the Oxford Centre for Evidence-based Medicine and the Consensus Health Economic Criteria (CHEC) list. RESULTS: Of a total of 693 studies, 16 studies were included. Comparison of TLIF and PLIF could only be made indirectly, since no study compared TLIF and PLIF directly. There was a large heterogeneity in health care and societal perspective costs due to different in-, and exclusion criteria, baseline characteristics and the use of costs or charges in calculations. Health care perspective costs, calculated with hospital costs, ranged from $15,867-$43,217 in TLIF-studies and $32,662 in one PLIF-study. Calculated with hospital charges, it ranged from $8,964-$51,469 in TLIF-studies and $21,838-$93,609 in two PLIF-studies. Societal perspective costs and cost-effectiveness, only mentioned in TLIF-studies, ranged from $5,702/QALY-$48,538/QALY and $50,092/QALY-$90,977/QALY, respectively. Overall quality of studies was low. CONCLUSIONS: This systematic review shows that TLIF and PLIF are expensive techniques. Moreover, firm conclusions about the preferable technique, based on (partial) economic evaluations, cannot be drawn due to limited studies and heterogeneity. Randomized prospective trials and full economical evaluations with direct TLIF and PLIF comparison are needed to obtain high levels of evidence. Furthermore, development of guidelines to perform adequate economic evaluations, specified for the field of interest, will be useful to minimize heterogeneity and maximize transferability of results. TRIAL REGISTRATION: Prospero-database registration number: CRD42020196869.

Cost-effectiveness of open transforaminal lumbar interbody fusion (OTLIF) versus minimally invasive transforaminal lumbar interbody fusion (MITLIF): a systematic review and meta-analysis.

BACKGROUND CONTEXT: The number of performed instrumented lumbar spine surgeries and associated health-care-related costs has increased over the last decades, and will increase further in the future. With the consistent growth of health-care-related costs, cost-effectiveness of surgical techniques is of major relevance. Common indications for instrumented lumbar spine surgery are spondylolisthesis and degenerative disease. A commonly used technique is the open transforaminal lumbar interbody fusion (OTLIF). Nowadays, there is an increasing interest in the minimally invasive variation of this technique (minimally invasive transforaminal lumbar interbody fusion [MITLIF]). Currently available literature describes that MITLIF has comparable or even better clinical results compared to OTLIF. Cost-effectiveness of MITLIF and OTLIF is important considering the growing health-care related costs, although no consensus has been reached regarding the most cost-effective technique. In this systematic review, previous literature concerning costs and cost-effectiveness of OTLIF was compared with MITLIF in patients with lumbar spondylolisthesis or degenerative disease. Furthermore, methodological quality of included studies was assessed. PURPOSE: This study aims to evaluate the current literature on cost-effectiveness of OTLIF compared MITLIF to in patients with lumbar spondylolisthesis or degenerative disease. STUDY DESIGN: This study is a systematic literature review and meta-analysis. STUDY SAMPLE: Clinical studies reporting costs or cost-effectiveness for either OTLIF or MITLIF in patients with spondylolisthesis, lumbar instability, or degenerative disease were included. OUTCOME MEASURES: The following data items were evaluated: study design, study population, utility measurement tool, gained quality adjusted life years (QALYs), cost sources, health care and societal perspective costs, total costs, costs per QALY (cost-effectiveness) and incremental cost-effectiveness ratio (ICER). METHODS: A systematic search was conducted using databases PubMed, CINAHL, EMBASE, Cochrane, Clinical Trials, Current Controlled Trials, ClinicalTrials.gov, NHS Centre for Review and Dissemination, Econlit and Web of Science on studies reporting OTLIF or MITLIF, spondylolisthesis or lumbar instability or degenerative disease, and costs. Relevant studies were selected and reviewed independently by two authors. For comparison, all costs were converted to American dollars with the reference year 2018. RESULTS: After duplicate removal, a total of 892 studies were identified. Eventually, 32 studies were included. Nine studies compared OTLIF and MITLIF directly. All studies mentioned health care perspective costs. Seven studies mentioned societal perspective costs. Cost-effectiveness of OTLIF was mentioned in five studies, ranging from $47,303/QALY to $218,766/QALY. Cost-effectiveness of MITLIF was mentioned in one study, $121,105/QALY. Meta-analysis of hospital perspective costs showed a significant overall effect in favor of MITLIF, with a mean difference of $2,650. There was great heterogeneity in health care and societal perspective costs due to different in-, and exclusion factors, baseline characteristics, and calculation methods. Overall quality of studies was low. CONCLUSIONS: OTLIF and MITLIF appear to be expensive interventions when using a threshold of $50,000/QALY. Results of this study and previous literature suggest that MITLIF is more cost-effective compared to OTLIF. Considering the increase in health care costs of instrumented spine surgery, cost-effectiveness could be one of the factors in surgical decision-making. Prospective randomized studies directly comparing cost-effectiveness of OTLIF and MITLIF from both hospital and societal perspectives are needed to obtain higher level of evidence.

Neurological events due to pedicle screw malpositioning with lateral fluoroscopy-guided pedicle screw insertion.

OBJECTIVE: The risk of novel postoperative neurological events due to pedicle screw malpositioning in lumbar fusion surgery is minimized by using one of the several image-guided techniques for pedicle screw insertion. These techniques for guided screw insertion range from intraoperative fluoroscopy to intraoperative navigation. A practical technique consists of anatomical identification of the screw entry point followed by lateral fluoroscopy used for guidance during insertion of the screw. This technique is available in most clinics and is less expensive than intraoperative navigation. However, the safety of lateral fluoroscopy-guided pedicle screw placement with regard to novel postoperative neurological events due to screw malposition has been addressed only rarely in the literature. In this study the authors aimed to determine the rate of novel postoperative neurological events due to intraoperative and postoperatively established screw malpositioning during lateral fluoroscopy-assisted screw insertion. METHODS: Included patients underwent lateral fluoroscopy-assisted lumbosacral screw insertion between January 2012 and August 2017. The occurrence of novel postoperative neurological events was analyzed from patient files. In case of an event, surgical reports were screened for the occurrence of intraoperative screw malposition. Furthermore, postoperative CT scans were analyzed to identify and describe possible screw malposition. RESULTS: In total, 246 patients with 1079 screws were included. Novel postoperative neurological events were present in 36 patients (14.6%). In 8 of these 36 patients (3.25% of the total study population), the neurological events could be directly attributed to screw malposition. Screw malpositioning was caused either by problematic screw insertion with immediate screw correction (4 patients) or by malpositioned screws for which the malposition was established postoperatively using CT scans (4 patients). Three patients with screw malposition underwent revision surgery without subsequent symptom relief. CONCLUSIONS: Lateral fluoroscopy-assisted lumbosacral screw placement results in low rates of novel postoperative neurological events caused by screw malposition. In the majority of patients suffering from novel postoperative neurological events, these events could not be attributed to screw malpositioning, but rather were due to postoperative neurapraxia of peripheral nerves, neuropathy, or intraoperative traction of nerve roots.

[Lumbar spondylolisthesis; common, but surgery is rarely needed]. / Lumbale spondylolisthesis.

Lumbar spondylolisthesis is usually asymptomatic. However, symptomatic spondylolisthesis results in back and/or leg pain such as radicular syndrome or neurogenic claudication. Variation in symptoms is caused by different types of spondylolisthesis. Lytic spondylolisthesis, most common at L5S1, is caused by spondylolysis of the pars interarticularis. This results in foraminal nerve compression and radicular symptoms. Degenerative spondylolisthesis, most common at L4L5 in patients >50 years old, is caused by slippage of the vertebral body and lamina, resulting in lumbar spinal stenosis and neurogenic claudication. Iatrogenic spondylolisthesis develops in 1.6-32.0% of patients after decompression surgery, causing recurrent neurogenic symptoms. It is important to understand the main symptoms patients experience: back or leg pain. In both cases, the preferred treatment is conservative. Surgery is only an option if patients have persistent/progressive leg pain. Shared decision-making is necessary to select the most accurate surgery for each individual patient while also taking into account age, comorbidities and symptoms. Further research is necessary to determine the advantages of each surgery in order to improve advice to patients.

Lumbar Interbody Fusion: A Historical Overview and a Future Perspective.

: In this historical study we present an overview of lumbar interbody fusion surgery, which is one of the most commonly performed instrumented spinal fusion surgeries. The present article focuses on the history of lumbar interbody fusion surgery, starting from the foundation which was laid in the 19th and 20th century until today. The development of material and techniques evolved from simple wiring to the combination of transforaminal interbody fusion with polyether ether ketone cages and pedicle screw fixation with poly axial screws. The possibilities of instrumented spinal fusion grew during the past 100 years, and a considerable increase in instrumented spinal surgery was seen over the past decades. Today, gain lies in perfection of techniques and deliberate indication and development of guidelines. Therefore, more standardized studies on instrumented spinal surgery are needed to be done and techniques should be personalized on the patients' specific needs. LEVEL OF EVIDENCE: N/A.

Transforaminal lumbar interbody fusion (TLIF) versus posterior lumbar interbody fusion (PLIF) in lumbar spondylolisthesis: a systematic review and meta-analysis.

BACKGROUND CONTEXT: Transforaminal lumbar interbody fusion (TLIF) and posterior lumbar interbody fusion (PLIF) are both frequently used as a surgical treatment for lumbar spondylolisthesis. Because of the unilateral transforaminal route to the intervertebral space used in TLIF, as opposed to the bilateral route used in PLIF, TLIF could be associated with fewer complications, shorter duration of surgery, and less blood loss, whereas the effectiveness of both techniques on back or leg pain is equal. PURPOSE: The objective of this study was to compare the effectiveness of both TLIF and PLIF in reducing disability, and to compare the intra- and postoperative complications of both techniques in patients with lumbar spondylolisthesis. STUDY DESIGN/SETTING: A systematic literature review and meta-analysis were carried out. METHODS: We conducted a Medline (using PubMed), Embase (using Ovid), Cochrane Library, Current Controlled Trials, ClinicalTrials.gov and NHS Centre for Review and Dissemination search for studies reporting TLIF, PLIF, lumbar spondylolisthesis and disability, pain, complications, duration of surgery, and estimated blood loss. A meta-analysis was performed to compute pooled estimates of the differences between TLIF and PLIF. Forest plots were constructed for each analysis group. RESULTS: A total of 192 studies were identified; nine studies were included (one randomized controlled trial and eight case series), including 990 patients (450 TLIF and 540 PLIF). The pooled mean difference in postoperative Oswestry Disability Index (ODI) scores between TLIF and PLIF was -3.46 (95% confidence interval [CI] -4.72 to -2.20, p≤.001). The pooled mean difference in the postoperative VAS scores was -0.05 (95% CI -0.18 to 0.09, p=.480). The overall complication rate was 8.7% (range 0%-25%) for TLIF and 17.0% (range 4.7-28.8%) for PLIF; the pooled odds ratio was 0.47 (95% CI 0.28-0.81, p=.006). The average duration of surgery was 169 minutes for TLIF and 190 minutes for PLIF (mean difference -20.1, 95% CI -33.5 to -6.6, p=.003). The estimated blood loss was 350 mL for TLIF and 418 mL for PLIF (mean difference -43.9 mL, 95% CI -71.2 to -16.6, p=.002). CONCLUSIONS: TLIF has advantages over PLIF in the complication rate, blood loss, and operation duration. The clinical outcome is similar, with a slightly lower postoperative ODI score for TLIF.